This invention relates to generators and, more particularly, to an end band for a generator.
A generator system, such as that found in aircrafts, ships, and some terrestrial vehicles, may include three separate generators, a permanent magnet generator (PMG), an exciter, and a main generator. Rotation of the rotor of the PMG induces an alternating current in the stator of the PMG. This alternating current is commonly sent through a rectifier where it is converted to an output as a direct current. This direct current is provided to the stator of the exciter and as a result of rotation of the exciter rotor, creates and alternating current output. Rectifier circuits rectify this alternating current and the resulting direct current is provided to the rotor of the main generator. As the rotor of the main generator rotates, alternating current is induced in the main generator stator and this can be output to the system. The components of a rotor of all of these generators must remain in place during rotation. To this end and by way of example, the exciter rotor typically includes a pair of end bands that hold critical parts of the exciter rotor in a desired position while withstanding the centrifugal forces and hoop stress acting on it.
Historically, end bands have been made of high strength, critical alloys well suited for use in extreme environments of pressure and heat. Presently, end bands are machined from a solid piece of bar stock having a diameter at least equal to the outside diameter of the end band. Because each end band is a hollow cylinder of a generally narrow thickness, the majority of the bar stock used to create each part is, therefore, wasted making the cost per part expensive relative to the percentage of the material used. Another method for forming an end band includes welding a rolled sheet to form a band. However, this welding method may be equally cost prohibitive because of the minimal tolerances required for the band.